The Lektropacks AV Guide
 
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Surround Sound / Dolby Digital

One of the most exciting aspects of Home Theatre is the ability to produce 5.1 channels of high quality audio in your own living room. Many of us who invested in Prologic decoders are now looking at Dolby Digital. New formats like DSS, DVD-Video and High Definition Television incorporate this new technology

Dolby Digital, developed by the Dolby Laboratories, was first introduced in 1992 with the movie 'Batman Returns'.

After Dolby Surround and Dolby Pro Logic, Dolby Digital was also a step farther for home theatre systems.

Dolby Digital provides six digital audio channels, the format '5.1'. The '5' channels are: Left, Centre, Right, Left-Surround, and Right-Surround. The '.1' represents the so-called LFE (Low Frequency Effect) channel, the limited bandwidth low-frequency subwoofer channel. These six channels are coded with the AC-3 coding, a coding format with very effective data rate reduction to store or transmit the large amount of data economically. Dolby AC-3 combines high quality sound with remarkable data rate efficiency.

Dolby Surround in comparison with a single and band-limited surround channel, that is used for two speaker channels, Dolby Digital implements the three front channels and two completely independent surround channels, each offering the same full range fidelity.

DVD players is the most common domestic piece of AV equipment that supports Dolby Digital, early DVD players tended to have a digital decoder built in, giving the units a decoded 6 phono Dolby Digital analogue output which would be connected to a analogue 5.1 inputs of a Surround Sound amp.

To reduce the cost of DVD players many manufacturers now only give a digital Dolby output leaving the decoding of the digital signal to be done by an amplifier, using either a coaxial phono (RCA) connection or an Optical Toslink style connector.


Analogue Surround sound. The colour coded "RCA" connectors are still red and White, designating "analogue" but instead of "L" and "R", you have "C" (centre), "FR" (front right), "FL" (front left), "SL" (surround left), "SR" (surround right), and "SW" (subwoofer). For Dolby Digital or DTS 6.1 or 7.1 there will be more! Surround sound analogue connections on computer sound cards use "mini" phono plug connections


Digital Audio connections, Coax on left, Toslink Optical on the right. Digital Coax uses orange colour coded "RCA" connections. These support AC3, Dolby Digital (5.1, etc.), DTS, S/PDIF. Use either connection, not both.

For converters see General Audio.


You will almost certainly need to use a combination of the analogue (red and white colour coded connections on the left) and the Digital connections on the right to connect all of your Home Theatre/Stereo system devices to your Surround sound Receiver. This receiver, like most has two Digital Audio inputs. One Coaxial and one Toslink. The second Toslink connector is for output. Use your DVD for one Digital input and either Digital Satellite Receiver, Digital Cable box, or CD player for the other. Which one uses Coax and which one uses Toslink depends on the capabilities of the devices you have to connect. Use the analogue connections for devices with no Digital output.

Suitable Lektropacks cables:  IQNOT, SSVL4SSFOTTHCFOTT.

Also see Analogue Audio & Digital Audio, Coaxial/SPDIF & Toslink/Fibre Optic Connections Explained.